Crystalline compositions conforming generally to the empirical formula Li.sup.+ (RCOO.sup.-).multidot.2Al(OH).sub.3 .multidot.nH.sub.2 O, where RCOO.sup.- represents an organic acid anion, are disclosed, inter alia, in U.S. Pat. No. 4,348,295, U.S. Pat. No. 4,348,296, and U.S. Pat. No. 4,348,297. These 3 patents are incorporated herein by reference. Other relevant background patents are U.S. Pat. No. 4,116,856; U.S. Pat. No. 4,116,858, U.S. Pat. No. 4,159,311; U.S. Pat. No. 4,221,767; U.S. Pat. No. 4,347,327; U.S. Pat. No. 4,321,065; U.S. Pat. No. 4,376,100; and U.S. Pat. No. 4,381,349, all of which disclose related lithium aluminates.
Also disclosed are Crystalline LiX.multidot.2Al(OH).sub.3 .multidot.nH.sub.2 O compounds and derivatives thereof, e.g., where the X anion represents OH, halide, halo acid, inorganic acid, organic acid and others. The compounds are referred to generally as "lithium aluminates" and are prepared, principally, by reacting lithium compounds with hydrous alumina and forming crystalline LiX.multidot.2Al(OH).sub.3 .multidot.nH.sub.2 O which in some cases are of the "two-layer" variety and in some cases of the "three-layer" variety, depending on the particular method or materials employed. Methods for preparing these known crystalline lithium aluminates, of the LiX.multidot.2Al(OH).sub.3 .multidot.nH.sub.2 O and LiOH.multidot.2Al(OH).sub.3 .multidot.nH.sub.2 O formulae, both 2-layer and 3-layer varieties, and anion exchanges or replacements in the crystals, are disclosed in the patents identified above, especially those incorporated by reference.
There are various polymers and resins which are used as coatings for substrates that are subject to deleterious attack by halogens or inorganic acid ions contained in the polymers and resins. These polymers and resins may be of the thermoplastic variety or of the thermosetting variety. The halogen or inorganic acid groups may be present (though usually unwelcome) as catalyst residues, polymerization aids, processing aids, impurities, or contaminants, or may be residual reaction products which are difficult to remove. For example, when olefin polymers are prepared using a halogen-containing metal catalyst (such as the well-known Ziegler catalyst or Natta catalyst or variations of these) the polymers ordinarily contain a catalyst residue which contains halogen groups. As another example, epoxy resins, prepared by reacting bisphenol A with epichlorohydrin to produce bis-oxirane molecules, contain a chlorine-containing reaction residue which is difficult to remove. There are other liquid (or liquifiable) organic or hydrocarbons which, if they contain extraneous halides, are beneficially treated with the halide scavengers of the present invention.
There are a number of commercially available compounds that are used, as additives, to control HCl levels in polymers. These stabilizers are designed to either neutralize HCl or to neutralize the HCl and reduce the Cl.sup.- solubility. Since soluble halides would be detrimental in many of the applications in which we are interested, only compounds which can reduce the halide concentration, not add to it, are of interest here. A large number of lead salts are used in PVC wire and cable coatings. Such compounds include basic lead carbonate, monobasic and tribasic lead sulfates, dibasic lead phthalate, basic lead sulfate/phthalate, lead sulfate/silicate complexes, dibasic lead phosphite and normal and dibasic stearates. These compounds would probably not be useful for applications such as controlling corrosion of semiconductors because PbCl.sub.2 is too soluble. The electronics industry has very stringent requirements concerning soluble metal salt levels. They may be useful in other types of epoxy coatings.
Another disadvantage to lead compounds is their extreme toxicity. The present lithium aluminate compounds used in the present invention have not been found to exhibit acute toxicity problems.
For purposes of conciseness, we shall use the terms liquid "resin" and "resinous material" in a general sense in this disclosure to mean polymers, plastics, resins, prepolymers, resin precursors, cured resins, uncured resins, and the like, which are in a liquid state, including melts or solutions thereof. The terms "organic" and "hydrocarbon" are used herein for non-aqueous materials which may not usually be called resins or polymers, but which contain halide values removable by the present inventive method.